title: Monte Carlo simulation of photon buildup factors for shielding materials in radiotherapy x-ray facilities.
abstract: OBJECTIVE
  This paper presents the results of a series of calculations to determine buildup factors for ordinary concrete, baryte concrete, lead, steel, and iron in broad beam geometry for photons energies from 0.125 to 25.125 MeV at 0.250 MeV intervals.
  
  
  METHODS
  Monte Carlo N-particle radiation transport computer code has been used to determine the buildup factors for the studied shielding materials.
  
  
  RESULTS
  The computation of the primary broad beams using buildup factors data was done for nine published megavoltage photon beam spectra ranging from 4 to 25 MV in nominal energies, representing linacs made by the three major manufacturers. The first tenth value layer and the equilibrium tenth value layer are calculated from the broad beam transmission for these nine primary megavoltage photon beam spectra.
  
  
  CONCLUSIONS
  The results, compared with published data, show the ability of these buildup factor data to predict shielding transmission curves for the primary radiation beam. Therefore, the buildup factor data can be combined with primary, scatter, and leakage x-ray spectra to perform computation of broad beam transmission for barriers in radiotherapy shielding x-ray facilities.
authors.affiliation: Faculté des Sciences de Monastir, Avenue de l'environnement 5019 Monastir, Tunisia.
authors.forename: Mohamed Karim
authors.initials: MK
authors.lastname: Karoui
authors.forename: Hedi
authors.initials: H
authors.lastname: Kharrati
mesh_terms: D003252:Construction Materials; D007854:Lead; D009010:Monte Carlo Method; D017785:Photons; D011835:Radiation Protection / Q000379:methods*; D013232:Steel; D014964:X-Ray Therapy
chemical_list: D013232:Steel; D007854:Lead